EP3271132B1

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Publication number: EP3271132B1
Application number: EP16710479.3A
Authority: EP
Inventors: François Mordasini; Gérard GAUTIER; Wayne Smith
Original assignee: North Thin Ply Technology Sarl
Current assignee: North Thin Ply Technology Sarl
Priority date: 2015-03-20
Filing date: 2016-03-18
Publication date: 2019-05-22
Anticipated expiration: 2036-03-18
Also published as: KR20170130518A; EP3271132B8; US10632353B2; EP3069848A1; EP3271132A1; WO2016150881A1; US20160271465A1; JP2018512223A; JP6559796B2; US10272302B2; EP3069848B1; US20180161647A1; CN107645983A; ES2738411T3; WO2016150883A1

Description

FIELD OF THE INVENTION

The present invention relates to a sports article comprising an elongate tubular shaft comprised of a fiber-reinforced resin matrix composite material. The present invention also relates to a method for manufacturing such an elongate tubular shaft comprised of a fiber-reinforced resin matrix composite material.

BACKGROUND OF THE INVENTION

Generally, a composite tube is produced by a method in which prepreg material is wound in a superposed manner around a metallic mandrel, then pressure is applied with a compacting system on this composite structure, then the thermoset and/or thermoplastic resin matrix is consolidated, and then the mandrel is removed from the product. Prepreg material is widely used in the manufacture of composite parts and structures. Prepreg material is a combination of thermoset and/or thermoplastic resin matrix and fiber reinforcement. The fibers of prepreg material are continuous fibers that extend parallel to each other. Preform is created by stacking individual layers of unidirectional tape optionally with different types of fiber, different resin matrix and/or different ply weight so that the layers of the preform contain fibers extending in different directions.
To improve the performance of the composite tube when submitted to loading specific to its use, the major portion of the reinforcing fibers of the preform should be oriented in order to improve the performance of the tube. However, existing manufacturing methods do not permit to achieve such a result at a high level of quality and without badly impacting on the homogeneity of the tube. In particular, such composite tubes are generally made by a roll wrapping process. Roll wrapping consists of wrapping preforms or individual layers of prepreg material having the same length as the tube and a width corresponding to a certain number of revolutions around the mandrel. Thus, the beginning and end of each wrapped preform or layer results in a defect in the tube. Furthermore, this roll wrapping process may require several steps to achieve the total required thickness and the quality of the tube depends on the skill and experience of the operator.
It is known to manufacture sports articles such as golf club shafts, fishing rods, rackets, etc. from a fiber-reinforced resin matrix composite material, in particular a carbon fiber composite material. However, elongate tubular shafts of carbon fiber composite material tend to suffer from the problem of exhibiting non-uniform properties, in particular a non-uniform wall thickness which leads to undesired variations in flexural stiffness along the shaft and when the flexural force is applied in different rotational orientations around the axis of the shaft.US-A-4000896 discloses a sports article comprising an elongate tubular shaft comprised of a fiber-reinforced resin matrix composite material, and method of manufacturing an elongate tubular shaft comprised of a fiber-reinforced resin matrix composite material.
US-A-2004/092329 discloses a hollow golf club shaft comprising a metallic cover layer, a vibration damping layer comprising a viscoelastic material and a core layer. A bladder-covered mandrel is wrapped with resin-impregnated reinforcement fibers to form the core layer. Typically, prepregs are draped or laid up over the mandrel, so that the uni-directional fibers are aligned at 0° to the longitudinal axis of the shaft. Plies of prepregs having fiber alignment angles of from about 30° to about 150° relative to the shaft axis are preferably used to provide additional torsional stiffness, particularly to critical areas such as the tip portion. The viscoelastic material may be spin-sprayed onto the inner surface of the cover layer.
US-A-5256230 discloses the helical winding of multiple tows upon a mandrel to form a tube.
The aim of the present invention is therefore to at least partially to overcome this problem with known shafts and to provide an improved sports article comprising an elongate tubular shaft comprised of a fiber-reinforced resin matrix composite material and manufacturing method, in particular in which the elongate tubular shaft can exhibit constant flexural properties by providing tubular shaft which has a highly concentric wall structure, with a uniformly controlled wall thickness around the axis of the shaft and accurate control of fiber alignment around the axis of the shaft.

SUMMARY OF THE INVENTION

The present invention provides a sports article according toclaim 1.
Preferred features of the sports article are defined independent claims 2 to 8 and 16.
The present invention also provides a method of manufacturing an elongate tubular shaft comprised of a fiber-reinforced resin matrix composite material, the method being according to claim 9.
Preferred features of the method are defined independent claims 10 to 16.
The preferred embodiments of the present invention can provide an elongate tubular shaft for use in a sports article which can have highly concentric plies of carbon to provide a symmetric shaft with no spine. The shaft can exhibit highly homogeneous flexural and torque behavior as a result of a very high degree of fiber alignment and uniformity of thickness around the shaft. Carbon fibers are longitudinally aligned along the shaft to provide flexural stiffness, but since the longitudinally aligned carbon fibers are discontinuous, i.e. extend only along a portion of the shaft as a result of helical wrapping of fibrous layers to form the hollow tubular shaft, there is a very high uniformity of flexural stiffness around the shaft and also the flexural stiffness can be accurately and predictably varied along the length of the shaft without reducing rotational homogeneity around the shaft. The wrap angle can be controlled to provide a perfect elongated conical shape for the shaft, with a highly uniform wall thickness around the shaft. This can provide a highly uniform longitudinal flexural stiffness when tested at different angles of rotation around the longitudinal axis of the shaft, for example having a variation of less than +/- 0.5 % at any angle measured within the range of 360 degrees around the shaft. The wrap overlap can be readily controlled to vary the stiffness along the shaft. The discontinuous longitudinal fiber structure can also provide with control of the wrap angle and/or overlap a very smooth wall thickness transition from relatively thick to relatively thin laminate at opposite ends of the shaft. Such smooth thickness variations are particularly desired in golf club shafts to provide uniformly predictable mechanical properties along and around the shaft. The longitudinal and helical structural fibers provide a biaxial fiber construction along the shaft to control the torsional stiffness of the shaft.
The method to manufacture the elongate tubular shaft in the sports article of the present invention permits to apply multiple layers of prepreg material at the same time such that the proportion of unidirectional fibers which are orientated in the performing direction are greater than the proportion of unidirectional fibers which are obliquely orientated relative to said performing direction. Furthermore, the method of the present invention permits to control the presence of overlaps, non-overlaps or gaps between the adjacent turns of the winding, thus improving the quality of the tube. This method also permits a reduction of the manufacturing costs.
This method further enables production of tubes in a continuous way with different mandrels arranged to follow each other in a sequence which lead to an improvement of the production rate.
Winding a preform with this method controls tension in the preform in order to obtain a better homogeneity and facilitate the improved quality of thick tubes.
Finally, this method confers consistency to tube properties because it allows more control of the orientation of the fibers in the case of tapered and/or arbitrarily shaped section tubes with the adjustment of the shape of the preform and/or the applied angle of the preform after two applications of preforms on the tube.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the present invention will appear more clearly from the detailed description of several embodiments of the invention which are illustrated by the attached drawings in which:

Figure 1 is a diagrammatic representation of a preform that is suitable for use to produce the sports article of an embodiment of the present invention;
Figures 2a and 2b are schematic views illustrating an apparatus that is suitable for use to produce the sports article of an embodiment of the present invention;
Figure 3a is a view similar toFigure 2b illustrating the butt joined preforms arrangement of a tube to produce the sports article of an embodiment of the present invention;
Figure 3b is a view similar toFigure 3a illustrating the overlapped preforms arrangement of a tube to produce the sports article of an embodiment of the present invention;
Figure 3c is a view similar toFigure 3a illustrating the spaced preforms arrangement of a tube to produce the sports article of an embodiment of the present invention;
Figures 4a and 4b illustrate an alternative apparatus that is suitable for use to produce the sports article of an embodiment of the present invention;
Figures 5a, 5b and 5c are schematic structural views illustrating another alternative apparatus that is suitable for use to produce the sports article of an embodiment of the present invention;
Figures 6a, 6b, 7a, 7b, 8a, 8b and9a, 9b illustrate several specific examples tubes that can be formed to produce the sports article of an embodiment of the present invention;
Figures 10a, 10b, 10c and10d illustrate several successive steps of a method to produce the sports article of an embodiment of the present invention;
Figures 10a, 10b, 10c and10d illustrate several successive steps of a method to produce the sports article of an embodiment of the present invention;
Figure 11 illustrates a side view of a composite tube manufactured according to an embodiment of the present invention which comprises an elongate tubular shaft of a sports article such as a golf club shaft;
Figure 12 is an enlarged cross-section through a wall portion of the elongate tubular shaft ofFigure 11;
Figure 13 is a further cross-section through the elongate tubular shaft ofFigure 11;
Figure 14 is an exploded perspective view of a preform tape to form a fibrous layer in the elongate tubular shaft ofFigure 11; and
Figure 15 is a golf club incorporating the elongate tubular shaft ofFigure 11.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Figure 1 illustrates an exemplary three-ply preform 10 suitable for use in a method to produce the sports article of an embodiment of the present invention. Thispreform 10 comprises afirst ply 12, a second ply 14 and a third ply 16, said first, second and third plies each including a thermoset and/or thermoplastic resin matrix and fibers. In the embodiment shown, the fibers in thefirst ply 12 are oriented in the 0° direction. The fibers in the second ply 14 are oriented in the 45° direction. The fibers in the third ply 16 are oriented in the 90° direction. Furthermore, each ply has its own ply thickness and mechanical properties. In the example, the ply thickness of the first and third plies is lower than the ply thickness of the second ply.
While the illustrated embodiment of the preformFigure 1 is a three-ply prefom, and the subsequentFigures 1 to 10 describe the use of that three-ply prefom to form an elongate tube, other embodiments of the present invention employ a two-ply preform, which is used to form a tubular shaft as described below. The preferred embodiment of a preform for manufacture of a sports article such as a golf club shaft is a two-ply preform, with the shaft comprising a laminate of two two-ply preforms to form a four-ply multilaminar structure. In the two-ply preform, as described below with reference to the perform tape, in the form of a prepreg tape, ofFigure 14, afirst ply 206 comprises parallel orientedfibers 104 which are oriented in a first direction and, after helical wrapping as described below, are oriented substantially longitudinally along the shaft and an adjacentsecond ply 208 comprises parallel orientedfibers 204 which are oriented in a second direction and, after helical wrapping as described below, are oriented helically around the shaft.
Figures 2a and 2b illustrate an example of the successive winding steps of the method according to one embodiment of the present invention. Thepreform 10 is firstly wound around atubular mandrel 20 so that the third ply 16 is oriented towards saidmandrel 20, the direction D of thefirst ply 12 defining an angle α with respect to the axis of the mandrel X, which is substantially equal to -45° in the example. Thus configured, the unidirectional fibers of the second layer 14 are substantially aligned with said axial direction X. Themandrel 20 may advantageously rotate around its own axis X. Thepreform 10 may advantageously be wound helically around themandrel 20. Each turn of the preform around themandrel 20 may overlap and/or be partially covered by another turn of the same, or may adjoin with its adjacent turns, or may be separated by a gap from its adjacent turns. Thepreform 10 is moved in the direction D1 until it reaches approximately a left end 21 of themandrel 20. Thereafter, thepreform 10 is reversed or changed in order to have theply 12 orientated at 45°. Thepreform 10 moves laterally in the opposite direction so as to permit the helical winding of thepreform 10 around themandrel 20 from its left end 21 to itsright end 23. During this winding operation, thefirst ply 12 is applied to themandrel 20 and the direction D of said first ply defines an angle α with respect to the axis X of the mandrel, such that the orientation of the fibers in one ply of thepreform 10 permits to improve a specific performance of the tube. In the embodiment shown, the angle α is substantially equal to +45°. Thus configured, the fibers of the second layer 14 are substantially aligned with said axial direction X, thus improving the performance of the tube when submitted to longitudinal loading. Simultaneously or afterwards, a strip of plastic imparting compacting pressure 11 is applied. Then, the structure formed by thepreform 10 is consolidated with the reticulation of the resin matrix.
The method to produce the sports article of an embodiment of the present invention is not limited to the above detailed embodiment. In particular, in further embodiments (not shown) of the present invention, the mandrel may be conical and/or define at least partially a portion of a torus and/or have a non-round section. Furthermore, the preform may have an alternative design. In particular, a trapezoidal or tapered preform may advantageously be used when the mandrel is conical when it is wanted to avoid an increasing overlap of the turns as the preform moves towards the end of the mandrel having the smallest diameter, which leads to an increasing wall thickness of the composite structure, or when it is wanted a tube having varying angles along its length. The number of preforms wound around the mandrel may also be greater than one. Furthermore, the number of plies of said preform may be three or more and the orientation of the fibers of said plies relative to the main direction of the preform may be any angle suitable for improving the performance of the composite structure. In any case, the parameters of the method of the present invention should be chosen so as to form a fiber-reinforced composite structure, in which the proportion of unidirectional fibers having a direction beneficial for the main performance of the composite structure is greater than the proportion of unidirectional fibers obliquely orientated relative to said direction.
As illustrated inFigure 3a, thepreform 10 may advantageously be wound around themandrel 20 in such a manner that each turn of thepreform 10 around themandrel 20 adjoins with another adjacent turn of the same.
Alternatively, as illustrated inFigure 3b, thepreform 10 may also be wound around themandrel 20 in such a manner that each turn of thepreform 10 around themandrel 20 at least partially covers and/or is at least partially covered by another turn of the same. Thepreform 10 may also be wound around themandrel 20 in such a manner that each turn of thepreform 10 around themandrel 20 is spaced from the other turn of the same, as illustrated inFigure 3c.
Figures 4a and 4b illustrate the forward and return helical winding of apreform 10 around amandrel 20 by means of an alternative apparatus. Such an operation includes a first step consisting of displacing themandrel 20 in the axial direction D1, without rotating it, and, simultaneously, clockwise rotating around said axial direction aroll 22, from which is delivered thepreform 10. Theroll 22 moves along acircular guide 24 that is centered on said mandrel axis, thus leading to the helical winding of thetape 10 from a left end region R1 of themandrel 20 to a right end region R2 thereof. During this pass from left to right, theroll 22 is oriented at an angle β relative to the plane P defined by thecircular guide 24 so that the helical winding is done at an angle α with respect to the direction D1. In a second step, corresponding to a pass from right to left, the orientation of theroll 22 relative to thecircular guide 24 is modified so as to be at an angle -β relative to the plane P. Then, themandrel 20 moves in the direction D2 opposite to D1 and, simultaneously, the clockwise rotation of theroll 22 is maintained. The return helical winding is thus done at an angle -α with respect to the axial direction.
Figures 5a, 5b and 5c illustrate a further alternative apparatus permitting the winding operation of two preforms 10a, 10b and of a compacting tape 11 around amandrel 20. In this example, themandrel 20 is supported by several fork-shapedelement 25 adapted to guide the mandrel during its displacement along an axial direction D2. The apparatus comprises respectively aroll 22a around which is wound the preform 10a, aroll 22b around which is wound the preform 10b and a roll 22c around which is wound the compacting tape 11, saidroll 22a moving in a counterclockwise direction along acircular guide 24a, saidroll 22b moving in a clockwise direction along a circular guide 24b and said roll 22c moving in a clockwise or counterclockwise direction along acircular guide 24c. Each circular guide is fixed in a position perpendicular to the axis of the mandrel. In this alternative, multiple mandrels are arranged in order to follow each other in a sequence. Mandrels are then wound continuously one after the other without a stop between the production of each part, thus increasing the production rate.
Figures 6a, 7a, 8a and9a illustrate several examples of a composite tube that can be made to produce the sports article of an embodiment of the present invention. These examples should not be construed as limiting the scope of the invention in any way.
In the example shown inFigure 6a, themandrel 100 supports a plurality of windings of apreform 110 illustrated inFigure 7b. Thispreform 110 comprises three plies, one first ply having fibers orientated at 0° relative to the longitudinal direction D defined by thepreform 110, one second ply having fibers orientated at -45° relative to said longitudinal direction D and one third ply having fibers orientated at -90° relative to said longitudinal direction D. Thepreform 110 is wound on themandrel 100 such that its longitudinal direction D is orientated at 45° relative to an axial direction X defined by themandrel 100. Therefore, the fibers of the second ply are parallel to the axial direction X and the fibers of the first and third plies are orientated respectively at 45° and -45° relative to said axial direction X. Thus configured, the tube formed by the windings of thepreform 110 has improved performance when submitted to bending and torsion loadings. The ratio between the bending performance and the torsion performance depends on the thickness and properties of each ply.
In the example shown inFigure 7a, themandrel 200 supports a plurality of windings of apreform 210 illustrated inFigure 7b. Thispreform 210 comprises two plies, one first ply having fibers orientated at 45° relative to the longitudinal direction D defined by thepreform 210 and one second ply having fibers orientated at -45° relative to said longitudinal direction D. Thepreform 210 is wound on themandrel 200 such that its longitudinal direction D is orientated at 45° relative to an axial direction X defined by themandrel 200. Therefore, the fibers of the second ply are parallel to the axial direction X and the fibers of the first ply are orientated at 90° relative to said axial direction X. Thus configured, the tube formed by the windings of thepreform 210 has improved performance when submitted to bending or radial compression loadings.
In the example shown inFigure 8a, themandrel 300 supports a plurality of windings of apreform 310 illustrated inFigure 8b. Thispreform 10 comprises two plies, one first ply having fibers orientated at 5° relative to the longitudinal direction D defined by thepreform 310 and one second ply having fibers orientated at -85° relative to said longitudinal direction D. Thepreform 310 is wound on themandrel 300 such that its longitudinal direction D is orientated at 85° relative to an axial direction X defined by themandrel 300. Therefore, the fibers of the second ply are parallel to the axial direction X and the fibers of the first ply are orientated at 90° relative to said axial direction X Thus configured, the tube formed by the windings of thepreform 310 has improved performance when submitted to internal pressure loadings.
In the example according to the disclosure shown inFigure 9a, themandrel 400 supports a plurality of windings of apreform 410 illustrated inFigure 9b. Thispreform 410 comprises two plies, one first ply having fibers orientated at 0° relative to the longitudinal direction D defined by thepreform 10 and one second ply having fibers orientated at 90° relative to said longitudinal direction D. Thepreform 410 is wound on themandrel 400 such that its longitudinal direction D is orientated at 45° relative to an axial direction X defined by themandrel 400. Therefore, the fibers of the first and second plies are orientated respectively at 45° and -45° relative to said axial direction X. Thus configured, the tube formed by the windings of thepreform 410 has improved performance when submitted to torsion loadings.
Figures 10a, 10b, 10c and10d illustrate several successive steps of a method to produce the sports article of an embodiment of the present invention when a composite tube having a toroidal shape has to be made.
The first step, shown inFigure 10a, consists of partially covering the periphery of amandrel 500 with a plastic orsilicone bladder 501.
The second step, shown inFigure 10b, consists of helically winding apreform 510 around said covered mandrel as described above.
The third step, shown inFigure 10c, consists of separation of the set formed by thepreform 510 wound around thebladder 501 from themandrel 500.
The fourth step, shown inFigure 10d, consists of curving said bladder-preform set in order to shape it and, thereafter, position said set in a closed mold, before its consolidation. During the consolidation, pressure is applied inside the bladder so as to press the preform against the internal walls of the mold.
Due to the helical winding of the preform around the bladder, stresses and/or folds of the preform during the curving of the preform are avoided since the various parts of the preform slide on each other.
The composite tube manufactured according to any of the preceding embodiments may, in some embodiments, comprise a sports article comprising an elongate tubular shaft comprised of a fiber-reinforced resin matrix composite material, which preferably comprises carbon fibers. In particular, the sports article may be a shaft for a golf club.
A particular embodiment of such a shaft for a golf club is described below with reference toFigures 11 to 15.
Referring toFigures 11 to 13, which for the purpose of clarity of illustration are not to scale, width and thickness being exaggerated, the elongatetubular shaft 100 has a longitudinal direction L and the shaft includes at least twofibrous layers 102, 103, each of which is helically wrapped about a wrapping direction W extending along the longitudinal direction L to form the elongatetubular shaft 100 which is multilaminar. InFigure 11 the outerfibrous layer 102 is shown in bold and the inner fibrous layer 103, adjacent to and covered by the outerfibrous layer 102, is shown in phantom by dashed lines. Each fibrous layer comprises a prepreg, in particular fibres, for example carbon fibres, impregnated with a resin, such as a thermosetting resin, for example epoxy resin. The fibre dimensions and fibre packing within the prepreg may be any suitable values, as are well known to those skilled in the art. Such carbon fibre/epoxy resin prepregs are known in the art and available in commerce form a variety of different prepreg manufacturers.
Eachfibrous layer 102, 103 comprises a plurality of orientedstructural fibers 104 which are substantially aligned along the longitudinal direction so as to be oriented within +/- 10° of the longitudinal direction L. Typically, the orientedstructural fibers 104 are substantially aligned along the longitudinal direction L so as to be oriented within +/- 5°, optionally +/- 2°, of the longitudinal direction L.
Theshaft 100 comprises a plurality of thefibrous layers 102, 103 which are helically wrapped about the wrapping direction W to form the multilaminar elongatetubular shaft 100. In this embodiment, at least two of thefibrous layers 102, 103 are helically wrapped about opposite rotational helical directions H and H', optionally at equal and opposite helical wrapping angles α and α'. Typically, alternatingfibrous layers 102, 103 are helically wrapped about opposite rotational helical directions H and H', optionally at equal and opposite helical wrapping angles α and α'.
The helical wrapping is along a helical direction H, H' which is at an angle of from 5 to 45 degrees, optionally from 10 to 35 degrees, further optionally from 15 to 25 degrees, yet further optionally at about 20 degrees, to a plane perpendicular to the longitudinal direction L. Typically, the angle of the helical direction H, H' is constant along the length of the elongatetubular shaft 100.
The or eachfibrous layer 102, 103 comprises a plurality of orientedstructural fibers 104 which are substantially aligned along the longitudinal direction L. The orientedstructural fibers 104 have a length d, along the longitudinal direction, of less than the length D of the elongatetubular shaft 100 thereby to form discontinuousstructural fibers 104 serially oriented along the elongatetubular shaft 100. Typically, the elongatetubular shaft 100 has a length D of from 300 to 1500 mm.
In the preferred embodiments, thestructural fibers 104 are discontinuously aligned along the longitudinal direction L along substantially the entire length D of the elongatetubular shaft 100. Preferably, all of thefibers 104 in the elongatetubular shaft 100 which are aligned along the longitudinal direction L arediscontinuous fibers 104 which each respectively extend along only a portion of the elongatetubular shaft 100. Typically, thestructural fibers 104 have a length d, along the longitudinal direction L, of from 20 to 100 mm. 22. Thestructural fibers 104 are discontinuously aligned along the longitudinal direction L along substantially the entire length D of the elongatetubular shaft 100.
In the preferred embodiments, all of the structural fibers in the elongatetubular shaft 100 are discontinuous fibers which each respectively extend along only a portion of the elongatetubular shaft 100.
At least two of thefibrous layers 102, 103, optionally all of the fibrous layers, each respectively further comprise a plurality of helicalstructural fibers 204, shown inFigure 12, which are helically wound around the longitudinal direction L. The helicalstructural fibers 204 have a length in the longitudinal direction L of less than the length of the elongatetubular shaft 100 to form discontinuous helicalstructural fibers 204 serially oriented along the elongatetubular shaft 100.
Typically, as shown in particular inFigures 12 and14, thefibrous layers 102, 103 each respectively comprise first and secondadjacent plies 206, 208, thefirst ply 206 comprising the substantially longitudinally orientedstructural fibers 104 of the respectivefibrous layer 102, 103 and thesecond ply 208 comprising the helicalstructural fibers 204 of the respectivefibrous layer 102, 103. These first and secondadjacent plies 206, 208 are in apreform tape 207 as shown inFigure 14.
Thefibrous layers 102, 103 typically each respectively comprise a helically wrappedmulti-ply tape 207 as shown in planar form inFigure 14, comprising the first and secondadjacent plies 206, 208.
In other embodiments, there are more than two fibrous layers and each fibrous layer respectively comprises a helically wrapped tape comprising the first and secondadjacent plies 206, 208. Most typically, the helicalstructural fibers 204 are helically wound around the longitudinal direction L at an angle of 45 degrees to the longitudinal direction L.
Preferably, theshaft 100 comprises from 40 to 80 wt% of the substantially longitudinally orientedstructural fibers 104 and from 20 to 60 wt% of the helicalstructural fibers 204, most preferably helicalstructural fibers 204 which are helically wound around the longitudinal direction L at an angle of +/-45 degrees to the longitudinal direction L, each wt% being based on the total weight of thestructural fibers 104, 204.
In the preferred embodiment, the elongatetubular shaft 100 comprises an even number of first andsecond plies 206, 208 from a plurality offibrous layers 102, 103 sequentially helically wrapped in opposite rotational directions. For example, the elongatetubular shaft 100 comprises twofibrous layers 102, 103 which have been helically wrapped in opposite rotational directions. This typically provides a multi-ply structure having the following ply orientations relative to the longitudinal direction: 0°, + 45°, 0°, - 45°, although as described above alternative helical wrapping angles may be employed.
Typically, the at least onefibrous layer 102, 103 is helically wrapped with from 5 to 50 rotations about the wrapping direction W to form the elongatetubular shaft 100.
Thefibrous layer 102, 103 is helically wrapped about the wrapping direction W so that, as show inFigure 12, thestructural fibers 104 of eachhelical wrap 106 in the respectivefibrous layer 102, 103 at least partially overlap with thestructural fibers 104 of a longitudinally adjacent helical wrap 106'. Typically, thestructural fibers 104 of eachwrap 106 at least partially overlap with from 5 to 90% of the length d of the structural fibers of the longitudinally adjacent wrap 106'.
A degree of overlap between thestructural fibers 104 of eachwrap 106 may vary along the length of the shaft. Typically, the degree of overlap between thestructural fibers 104 of eachwrap 106 increases substantially continuously along the length D of theshaft 100. The degree of overlap between thestructural fibers 104 of eachwrap 106 may increase substantially linearly along the length D of theshaft 100. When theshaft 100 is substantially conical, as described further below, the degree of overlap decreases with increasing diameter of the substantiallyconical shaft 100.
Typically, thehelical wrap 106 has a width, orthogonal to the helical direction H, of from 10 to 140 mm, optionally from 15 to 50 mm, further optionally from 25 to 35 mm, still further optionally about 30 mm. This width is provided by employing a corresponding tape width during the manufacturing process as described hereinbefore in which tape is helically wound about a mandrel to form the fibrous layer. The width of thehelical wrap 106, orthogonal to the helical direction H, may vary along the length D of theshaft 100.
As shown inFigure 14, which shows atape 207 prior to winding to form thehelical wrap 106, typically, the width of thehelical wrap 106, orthogonal to the helical direction H, increases substantially continuously, and optionally substantially linearly, along the length D of theshaft 100. This is achieved by varying the width of thetape 207. When theshaft 100 is conical, as described further below, the width of thetape 207, and consequently of thehelical wrap 106, increases with increasing diameter of theconical shaft 100.
As shown schematically inFigure 13, in which the width dimensions of theshaft 100 are exaggerated for the purpose of clarity of illustration, the elongatetubular shaft 100 preferably has an external elongate substantiallyconical surface 108 and an internal elongate substantiallyconical surface 110, each substantiallyconical surface 108, 110 optionally comprising a series of adjoining conics as a result of the serial helical wraps 106. The external elongate substantiallyconical surface 108 and the internal elongate substantiallyconical surface 110 are inclined at different respective inclination angles β and δ relative to the longitudinal direction L. The inclination angle β of the external elongateconical surface 108 is smaller than the inclination angle δ of the internal elongateconical surface 110, each inclination angle β, δ being relative to the longitudinal direction L.
Accordingly, the wall thickness T of the elongatetubular shaft 100 decreases in combination with an increase in a diameter of the external elongateconical surface 108 along a length of the elongatetubular shaft 100. Typically, the wall thickness T of the elongatetubular shaft 100 decreases substantially continuously, and preferably substantially linearly, with the increase in diameter of the external elongateconical surface 108 along the length of the elongatetubular shaft 100.
As a result of the highly uniform wrapping configuration of thefibrous layer 102, 103 forming theshaft 100, the elongatetubular shaft 100 has a longitudinal flexural stiffness which is substantially uniform when measured in a measuring direction orthogonal to the longitudinal direction L at any angle of rotation relative to an axis coincident with the longitudinal direction L. Typically, the longitudinal flexural stiffness varies by less than +/- 0.5 % when measured in a measuring direction orthogonal to the longitudinal direction L at any angle of rotation relative to an axis coincident with the longitudinal direction L.
The elongatetubular shaft 100 typically has a weight of from 45 to 65 g. The elongatetubular shaft 100 also typically has a flexibility defined by a frequency of from 230 to 300 cycles per minute when theshaft 100 is flexed and then released in a flexing direction orthogonal to the longitudinal direction L at any angle of rotation about an angle of 360 degrees relative to an axis coincident with the longitudinal direction L. Preferably, the flexibility varies by no more than 5 cycles per minute at any angle of rotation about the angle of 360 degrees relative to the axis coincident with the longitudinal direction L. Typically, theshaft 100 has an angular movement under an applied torque of from 2 to 5 degrees, the angular movement being measured by applying 1.36 Nm (1 foot pound) of torque to the shaft at a first end of the shaft (typically the thinner tip) while clamping a second end of the shaft (typically the thicker butt end).
As described above, in a particularly preferred aspect of the present invention the elongatetubular shaft 100 is a golf club shaft 120, as shown inFigure 15. Typically, the golf club shaft 120 is conical and extends between ahandle end 122 and ahead end 124, with a diameter of the shaft 120 being greater at thehandle end 122 than at thehead end 124. Additionally or alternatively, a wall thickness of the shaft 120 is greater at thehead end 124 than at thehandle end 122.

Claims

A sports article comprising an elongate tubular shaft (100) comprised of a fiber-reinforced resin matrix composite material, wherein the elongate tubular shaft has a length (D) in a longitudinal shaft direction (L) and the shaft (100) is multilaminar and includes at least two fibrous layers (102, 103), each of which fibrous layers (102, 103)is helically wrapped about a wrapping direction (W) extending along the longitudinal shaft direction (L) to form the elongate tubular shaft (100), wherein each fibrous layer (102, 103) is helically wrapped about the wrapping direction (W) so that the structural fibers (104) of each helical wrap (106) at least partially overlap with the structural fibers (104) of a longitudinally adjacent helical wrap (106') and the helical wrap (106, 106') has a width, orthogonal to a helical direction (H, H'), of from 10 to 140 mm, wherein each fibrous layer (102, 103) comprises a plurality of oriented structural fibers (104) which are substantially aligned along the longitudinal shaft direction (L) so as to be oriented within +/- 10° of the longitudinal shaft direction (L), the oriented structural fibers (104) having a length (d), along the longitudinal shaft direction (L), of less than the length (D) of the elongate tubular shaft (100) to form discontinuous structural fibers (104) serially oriented along the longitudinal shaft direction (L) of the elongate tubular shaft (100).
The sports article according to claim 1 wherein the structural fibers (104) of each wrap (106) at least partially overlap with from 5 to 90% of the length (d) of the structural fibers (104) of the longitudinally adjacent helical wrap (106') and a degree of overlap between the structural fibers (104) of each helical wrap (106, 106') varies, optionally increasing substantially continuously or increasing substantially linearly, along the length (D) of the shaft (100).
The sports article according to claim 1 or claim 2 wherein the width of the helical wrap (106, 106'), orthogonal to the helical direction (H, H'), varies, optionally increasing substantially continuously or increasing substantially linearly, along the length (D) of the shaft (100).
The sports article according to any one of claims 1 to 3 wherein the elongate tubular shaft (100) has an external elongate substantially conical surface (108) and an internal elongate substantially conical surface (110), each substantially conical surface (108, 110) optionally comprising a series of adjoining conics,
optionally wherein the external elongate substantially conical surface (108) and the internal elongate substantially conical surface (110) are inclined at different respective inclination angles (β, δ) relative to the longitudinal shaft direction (L),
further optionally wherein the inclination angle (β) of the external elongate substantially conical surface (108) is smaller than the inclination angle (δ) of the internal elongate substantially conical surface (110), each inclination angle (β, δ) being relative to the longitudinal shaft direction (L), whereby the wall thickness (T) of the elongate tubular shaft (100) decreases in combination with an increase in a diameter of the external elongate conical surface (108) along the length (D) of the elongate tubular shaft (100),
yet further optionally wherein the wall thickness (T) of the elongate tubular shaft (100) decreases substantially continuously with the increase in diameter of the external elongate conical surface (108) along the length (D) of the elongate tubular shaft (100),
still further optionally wherein the wall thickness (T) of the elongate tubular shaft (100) decreases substantially linearly with the increase in diameter of the external elongate conical surface (108) along the length (D) of the elongate tubular shaft (100).
The sports article according to any one of claims 1 to 4 wherein
(i) the elongate tubular shaft (100) has a longitudinal flexural stiffness which is substantially uniform when measured in a measuring direction orthogonal to the longitudinal shaft direction (L) at any angle of rotation relative to an axis coincident with the longitudinal shaft direction (L), optionally wherein the longitudinal flexural stiffness varies by less than +/-0.5 % when measured in a measuring direction orthogonal to the longitudinal shaft direction (L) at any angle of rotation relative to an axis coincident with the longitudinal shaft direction (L),
and/or
(ii) the shaft (100) has a weight of from 45 to 65 g, a frequency of from 230 to 300 cycles per minute when the shaft (100) is flexed and then released in a flexing direction orthogonal to the longitudinal shaft direction (L) at any angle of rotation about an angle of 360 degrees relative to an axis coincident with the longitudinal shaft direction (L), optionally wherein the frequency varies by no more than 5 cycles per minute at any angle of rotation about the angle of 360 degrees relative to the axis coincident with the longitudinal shaft direction (L), further optionally wherein the shaft (100) has an angular movement of from 2 to 5 degrees, the angular movement being measured by applying 1.36 Nm (1 foot pound) of torque to the shaft (100) at a first end of the shaft (100) while clamping a second end of the shaft (100).
The sports article according to any one of claims 1 to 5 wherein the structural fibers (104) are discontinuously aligned along the longitudinal shaft direction (L) along substantially the entire length (D) of the elongate tubular shaft (100) and all of the structural fibers (104) in the elongate tubular shaft (100) which are aligned along the longitudinal shaft direction (L) are discontinuous fibers (104) which each respectively extend along only a portion of the elongate tubular shaft (100), optionally wherein the structural fibers (104) which are aligned along the longitudinal shaft direction (L) have a length (d), along the longitudinal shaft direction (L), of from 20 to 100 mm.
The sports article according to any one of claims 1 to 6 wherein at least two of the fibrous layers (102, 103) each respectively further comprise a plurality of helical structural fibers (204) which are helically wound around the longitudinal shaft direction (L), the helical structural fibers (204) having a length in the longitudinal shaft direction (L) of less than the length (D) of the elongate tubular shaft (100) to form discontinuous helical structural fibers (204) serially oriented along the elongate tubular shaft (100),
optionally
(i) wherein at least two of the fibrous layers (102, 103) each respectively comprise first and second adjacent plies (206, 208), the first ply (206) comprising the substantially longitudinally oriented structural fibers (104) of the respective fibrous layer (102, 103) and the second ply (208) comprising the helical structural fibers (204) of the respective fibrous layer (102, 103), , further optionally each of the at least two fibrous layers respectively comprising a helically wrapped tape (207) comprising the first and second adjacent plies (206, 208),
and/or
(ii) wherein the shaft (100) comprises from 40 to 80 wt% of the substantially longitudinally oriented structural fibers (104) and from 20 to 60 wt% of the helical structural fibers (204), optionally the helical structural fibers (100) being helically wound around the longitudinal shaft direction (L) at an angle of +/- 45 degrees to the longitudinal shaft direction (L), each wt% being based on the total weight of the structural fibers (104, 204).
The sports article according to any one of claims 1 to 7 wherein the elongate tubular shaft (100) is a golf club shaft (120) and the shaft (120) is substantially conical and extends between a handle end (122) and a head end (124), wherein a diameter of the shaft (120) is greater at the handle end (122) than at the head end (124) and/or a wall thickness of the shaft (120) is greater at the head end (124) than at the handle end (122).
A method of manufacturing an elongate tubular shaft (100) comprised of a fiber-reinforced resin matrix composite material, the tubular shaft (100) being suitable for manufacturing a sports article, the method comprising the steps of:
a) providing a first fibrous layer (102) comprising a prepreg;
b) helically wrapping the first fibrous prepreg layer (102) about a wrapping direction (W) extending along a longitudinal shaft direction (L) to form an elongate tube, the first fibrous layer (102) comprising a plurality of oriented structural fibers (104) which are substantially aligned along the longitudinal shaft direction (L) so as to be oriented within +/- 10° of the longitudinal shaft direction (L), the oriented structural fibers (104) having a length (d), along the longitudinal shaft direction (L), of less than the length (D) of the elongate tube to form discontinuous structural fibers (104) serially oriented along the elongate tube;
c) providing a second fibrous layer (103) comprising a prepreg;
d) helically wrapping the second fibrous layer (103) over the first fibrous layer (102), the second fibrous layer (103) being wrapped about the wrapping direction (W) extending along the longitudinal shaft direction (L) to provide the elongate tube with a multilaminar elongate tubular wall, the second fibrous layer (103) comprising a plurality of oriented structural fibers (104) which are substantially aligned along the longitudinal shaft direction (L) so as to be oriented within +/- 10° of the longitudinal shaft direction (L), the oriented structural fibers (104) having a length (d), along the longitudinal shaft direction (L), of less than the length (D) of the elongate tube to form discontinuous structural fibers (104) serially oriented along the elongate tube;
wherein in steps b) and d) each fibrous layer (102, 103) is respectively helically wrapped about the wrapping direction (W) so that in each fibrous layer (102, 103) the structural fibers (104) of each helical wrap (106) at least partially overlap with the structural fibers (104) of a longitudinally adjacent helical wrap (106'), and in steps b) and d) the respective helical wrap (106, 106') has a width, orthogonal to a helical direction (H, H'), of from 10 to 140 mm; and
e) heating and/or pressurising the elongate tube to form an elongate tubular shaft (100) extending along the longitudinal shaft direction (L) comprised of a fiber-reinforced resin matrix composite material.
The method according to claim 9 wherein in steps b) and d) each fibrous layer (102, 103) is respectively helically wrapped about the wrapping direction (W) so that in each fibrous layer (102, 103) the structural fibers 104) of each helical wrap (106) at least partially overlap with from 5 to 90% of the length (d) of the structural fibers (104) of the longitudinally adjacent helical wrap (106'), and so that in each fibrous layer (102, 103) a degree of overlap between the structural fibers (104) of each helical wrap (106, 106') varies, optionally increasing substantially continuously or increasing substantially linearly, along the length (D) of the shaft (100).
The method according to claim 9 or claim 10 wherein in steps b) and d) the respective helical wrap (106, 106') has a width, orthogonal to the helical direction (H, H'), of from 15 to 50 mm, optionally from 25 to 35 mm, further optionally about 30 mm.
The method according to any one of claims 9 to 11 wherein in steps b) and d) the width of the respective helical wrap (106, 106'), orthogonal to the helical direction (H, H'), varies, optionally increasing substantially continuously or increasing substantially linearly, along the length (D) of the shaft (100).
The method according to any one of claims 9 to 12 wherein step e) is carried out so that the elongate tubular shaft (100) formed in step e) has an external elongate substantially conical surface (108) and an internal elongate substantially conical surface (110), each substantially conical surface (108, 110) optionally comprising a series of adjoining conics,
optionally wherein the external elongate substantially conical surface (108) and the internal elongate substantially conical surface (110) are inclined at different respective inclination angles (β, δ) relative to the longitudinal shaft direction (L),
further optionally wherein the inclination angle (β) of the external elongate substantially conical surface (108) is smaller than the inclination angle (δ) of the internal elongate substantially conical surface (110), each inclination angle (β, δ) being relative to the longitudinal shaft direction (L), whereby the wall thickness (t) of the elongate tubular shaft (100) decreases in combination with an increase in a diameter of the external elongate conical surface (108) along the length (D) of the elongate tubular shaft (100),
yet further optionally wherein the wall thickness (T) of the elongate tubular shaft (100) decreases substantially continuously with the increase in diameter of the external elongate conical surface (108) along the length (D) of the elongate tubular shaft (100),
still further optionally wherein the wall thickness (T) of the elongate tubular shaft (100) decreases substantially linearly with the increase in diameter of the external elongate conical surface (108) along the length (D) of the elongate tubular shaft (100).
The method according to any one of claims 9 to 13 wherein in steps b) and d) the structural fibers (104) are discontinuously aligned along the longitudinal shaft direction (L) along substantially the entire length (D) of the elongate tubular shaft (100) and all of the structural fibers (104) in the elongate tubular shaft (100) which are aligned along the longitudinal shaft direction (L) are discontinuous fibers which each respectively extend along only a portion (d) of the elongate tubular shaft (100), optionally wherein in steps b) and d) the structural fibers (104) which are aligned along the longitudinal shaft direction (L) have a length (d), along the longitudinal shaft direction (L), of from 20 to 100 mm.
The method according to any one of claims 9 to 14 wherein in steps b) and d) at least two of the fibrous layers (102,103) each respectively further comprise a plurality of helical structural fibers (204) which are helically wound around the longitudinal shaft direction (L), the helical structural fibers (204) having a length in the longitudinal shaft direction (L) of less than the length (D) of the elongate tubular shaft (100) to form discontinuous helical structural fibers (204) serially oriented along the elongate tubular shaft (100),
optionally
(i) wherein in steps b) and d) at least two of the fibrous layers (102,103) comprising respective prepregs each respectively comprise first and second adjacent plies (206, 208), the first ply (206) comprising the substantially longitudinally oriented structural fibers (104) of the respective fibrous layer (102,103) and the second ply (208) comprising the helical structural fibers (204) of the respective fibrous layer (102,103), further optionally wherein in steps b) and d) at least two of the fibrous layers (102,103) each respectively comprise a helically wrapped prepreg tape (207) comprising the first and second adjacent plies (206, 208),
and/or
(ii) wherein steps b) and d) are carried out so that the multilaminar elongate tubular wall comprises from 40 to 80 wt% of the substantially longitudinally oriented structural fibers (104) and from 20 to 60 wt% of the helical structural fibers (204), optionally the helical structural fibers (204) being helically wound around the longitudinal shaft direction (L) at an angle of +/-45 degrees to the longitudinal shaft direction (L), each wt% being based on the total weight of the structural fibers (104, 204).
The sports article according to any one of claims 1 to 8 or the method according to any one of claims 9 to 15 wherein the oriented structural fibers (104) are substantially aligned along the longitudinal shaft direction (L) so as to be oriented within +/- 5°, optionally +/- 2°, of the longitudinal shaft direction (L).